Throughout a semiconductor device manufacturing process, a semiconductor wafer is cleaned to remove particles, such as contamination from a depositions system, from the surface of the semiconductor wafer. If the particles are not removed, the particles will contaminate the semiconductor wafer resulting in damage to the electronic devices on the semiconductor wafer. As such, cleaning operations define a very critical step that is repeated many times throughout the manufacturing process.
One method to clean the semiconductor wafer is to rinse the surface of the semiconductor wafer with deionized water. However, cleaning the semiconductor water with water is terribly inefficient because the process uses an immense amount of water to remove only a very minute amount of contaminant. Specifically, the inefficiency is caused by the Newtonian properties of water. FIG. 1 is a shear stress and strain diagram of water. The shear stress and strain diagram is a plot of a shear strain rate versus shear stress. As shown in FIG. 1, the shear strain rate and shear stress of water plot as a straight line on the diagram. Thus, water (and all Newtonian fluids) is characterized by having a shear stress that is linearly proportional to the shear strain rate. The plot goes through origin 101 of the diagram. Accordingly, any finite shear stress applied on the water can initiate flow. In other words, water has minimal or no yield point, which is the minimum force required to initiate flow in water.
FIG. 2 is a velocity flow profile for a flow of water on a surface of semiconductor wafer 202. As shown in FIG. 2, since water has virtually no yield point, the velocity of the water in contact with the surface of semiconductor wafer 202 is essentially zero and the velocity increases the further away from the semiconductor wafer. Accordingly, water is essentially stagnant at the point of contact with surface of semiconductor wafer 202. Since the water just above the surface of semiconductor wafer 202 is not moving, there is no mechanism for the flow of water to carry away particles at the surface of the semiconductor water. Accordingly, a large amount of water flow is needed to create any significant velocity at the surface of semiconductor wafer 202 to enable removal of particles from the surface.
In view of the foregoing, there is a need to provide methods and apparatuses that use fluids more efficiently to clean semiconductor wafers.